Salicylic acid esters of hydroxyalkylcarboranes



United States Patent 3,409,663 SALICYLIC ACID ESTERS OF HYDROXY-ALKYLCARBORANES Saiyid M. Naqvi, Dover, Martin J. Socha, Wayne, andMarvin M. Fein, Westfield, N.J., assignors to Thiokol ChemicalCorporation, Bristol, Pa., a corporation of Delaware No Drawing. FiledSept. 17, 1964, Ser. No. 397,292

1 Claim. (Cl. 260474) This invention concerns certain boron containingesters of aromatic acids, their preparation and their applications.

More particularly this invention relates to esters prepared by thereaction of carborane alcohols and carborane diols with aromatic acids.These least one carborane group as well as one or two reactive hydroxygroups whereas the term carborane diols as used herein describescompounds c formula: BC2H12- The term carboranyl is the name given tothe radical of the ortho carborane isomer shown below:

The ortho isomer is also referred to by the Greek letter theta,abbreviated as 0.

The radical of the para-isomer of carborane is referred to herein asparacarboranyl.

The radical of the meta isomer of carborane is referred to asneocarboranyl, abbreviated as G9.

The term aromatic acid(s) application refers to aromatic ac1d typereactants having stituents, such as halogen, hydroxy, alkoxy and thelike.

It is an object of this invention to prepare novel carborane esters.

It is an additional object of this invention to prepare compositionsuseful as ultraviolet absorbers and protectants.

A further object of this invention is to prepare polymer intermediatesand additives.

The other objects of this invention will become apparent after a furtherperusal of this application.

The above objects among others are achieved through the preparation ofthe esters of this invention.

In practice, a carborane reactant selected from the alcohols orcarborane diols can be used as sources of the hydroxyl group: thel-hydroxyalkylcarboranes such as 1-hydroxymethylcarborane,l-hydroxyethylcarborane, the 1-hydroxypropylcarboranes, thel-hydroxybutylcarboranes and the like, the 1-hydroxyalkylneocarboranes3,409,663 Patented Nov. 5, 1968 such as 1-hydroxybutylne0carboranes, thel-hydroxypentylneocarboranes, etc., thel,2-bis-(1-hydroxyalkyl)carboranes such as1,2-bis-hydroxymethylcarborane, 1,2-bis-(1- hydroxyethyl)carborane, the1,2-bis-(l-hydroxypropyl) carboranes, the1,2-bis-(l-hydroxybutyl)carboranes, etc., as well as thebis-(hydroxyalkyl)neocarboranes. These includebis-(hydroxyrnethyl)neocarborane, bis-(hydroxyethyl)neocarborane, thebis-(hydroxypropyl)neocarbofi-hydroxyethyl-l-carboranylmethyl) ether,bis (2-hydroxyethyl-l-carboranylmethyl) ether groups have 1-8 carbon thepreferred reactants and bis(hydroxyalkyl) carboranes wherein the alkylgroup has from 18 carbon atoms. These reactants are preferred becausethe resultant esters are good ultraviolet absorbers and the reactantsare more readily available.

Among the many actants which can be isophthalic acids, phthalicanhydride ing acid chlorides.

Further latitude exists in the solvents choice of reaction conditionssuch as the use used to prepare the novel compounds of this invenaninert solvent such as the aromatics. When such a solvent is used, i.e.benzene, the water is taken off as the water- C. After the addition iscomplete the reaction mixture is raised to about 60-120 C. for severalHCl by-product can The reaction time for esterification is shorter whenthe acid chlorides are used usually ranging between 21 hours.

When either the 'carboxylic acid, anhydride, ester or the acid chlorideis used as reactant, an excess of the aromatic carboxylic acid typereactant is used over that required by stoichiometry but this is not anecessity.

The isolation and purification procedures used are comparable to thatemployed .in organic chemistry for isolating and purifying esters of thealiphatic alcohols and for that reason will not be elaborated upon.Specific details appear in the embodiments and examples which follow.

In one embodiment of this invention, the neocarboranylmethyl ester ofsalicylic acid is prepared as follows.

-Mix neocarboranylmethyl alcohol and salicylic acid in 300 ml; ofbenzene in a reaction vessel fitted with a Dean-Stark apparatus. The tworeactants are present in the ratio of 121.05 respectively. A catalyticquantity of p-toluenesulfonic acid is added and the reaction mixture isbrought to reflux. During 8 hours of refluxing the water is removed as awater-benzene azeotrope. The reaction mixture is cooled down, filteredand the benzene stripped off under vacuum. The residue is treated withaqueous NaHCO to remove unreacted salicylic acid and the ester productis recrystallized from heptane, three times to give a colorless product,whose ultraviolet and infrared spectra and elemental analysis confirm itto be the expected product.

In another embodiment, add 0.55 mole of phthalyl chloride in 50 ml. ofxylene to a stirred solution of 0.25 mole of neocarboranylbutyl alcohol(l-hydroxybutylneocarborane) in 150 ml. of xylene. After the addition iscomplete, raise the temperature to 80 C. for 4 hours. At the end of thistime flush with nitrogen and cool to room temperature and strip off thexylene under vacuum. Neutralize with an aqueous solution of 5% NaHCO andfilter to recover the desired di-(neocarboranylbutyl) ester of phthalicacid.

Another embodiment is demonstrated by the following preparation of theneocarboranylmethyl ester of p-chlorobenzoic acid.

Slowly add a solution of 0.15 mole of p-chlorobenzoyl chloride in 100ml. of benzene to a stirred solution of 0.1 mole ofhydroxymethylneocarborane. After the addition is complete, raise thetemperature to 7 5-80" C. and heat for 3 hours. Flush, cool and stripoff solvent as above.

Yet another embod' ent is demonstrated by the preparation of theneocarboranylethyl ester of m-ethyl benzoic acid.

To prepare this ester, add a solution'of 0.25 mole of m-ethyl benzoylchloride in 100 ml. of toluene to a solution of 0.20 mole of(l-hydroxyethyl)neocarborane in 100 ml. benzene. After the addition ofacid chloride is complete, raise the temperature to- 80 C. and continueheating for 6 hours. Isolate and purify the ester as above to prepare ananalytically pure sample.

Still a further embodiment is the preparation of neocarboranylmethyldi-ester of salicylic acid.

To prepare this ester, slowly add a solution of 0.25 mole ofo-hydroxybenzoyl chloride in 100 ml. of benzene to 100 ml. solution ofbenzene containing 0.10 mole of bis-(hydroxymethyl) neocarborane. Heatto 80 C. for 5 hours after the addition is complete and isolate andpurify the ester as described previously.

In still a "further embodiment, the neocarboranylethyl di-ester of orthon-butyl benzoic acid is prepared as follows.

Add 0.25 mole of o-butyl benzoyl chloride in 100 ml. of benzene to astirred solution of 100 ml. of benzene containing 0.10 mol ofbis-(hydroxyethyl) neocarborane. After the addition is complete, heat to75 C. for 6 hours. Then flush with nitrogen to remove HCl and stripunder vacuum to remove benzene. Neutralize with 5% aqueous sodiumbicarbonate solution and filter toget the. crude ester product. The pureester can be obtained by recrystallization from cyclohexane.

In comparable embodiments the following alkylcarborane esters of benzoicand substituted benzoic acids are Prepared.

To prepare carboranylmethyl salicylate (carboranylmethyl ester ofsalicylic acid), combine l-hydroxymethylcarborane (0.11 mole) andsalicylic acid (0.1 mole) and 300 ml. of benzene in the presence of'p-toluenesulfonic acid in a reaction vessel fitted with a Dean-Starkapparatus. Reflux for 6 hours and remove' the water forme through theWater-benzene azeotrope. At the end of this time filter and strip offthe benzene under vacuum/The residue is treated with aqueous sodiumbicarbonate to remove untreated salicylic acid. Recrystallize the solidester from heptane three times to give colorless, nedle like crystalsmelting 112.5-114" C.

Analysis.-Calcd. for C I-I B O g: C, 40.8; H,"'6 .16; B, 36.72. Found:C, 40.89; H, 6.54; B, 36.51.

The UV spectrum (cyclohexane) reveals two maxiniai' To preparecarboranylmethyl benzoate (the carbora nylmethyl ester of benzoic acid)mix 1-carboranylrnethyl alcohol (8.8 g., 0.05 mole); benzoic acid (6.1g, 0.05 mole), p-toluenesulfonic acid 2 g., and 5 ml. of concentratedsulfuric acid in 100 ml. of benzene and reflux for three hours, removingwater formed as a water-benzene azeotrope using the Dean-Stark trap.Cool the reaction mixture and neutralize with 10% NaHCO solution.Separate the organic layer and strip off the solvent removed undervacuum. Recrystallize the solid residue several times from n-hexane togive colorless crystalline carboranylmethyl benzoate product, M.P. -96C.

Analysis.Calcd. for 0 111 13 0 C, 43.42; H, 6.51; B, 38.82. Found: C,43.41; H, 6.74; B, 38.13.

The UV spectrum (cyclohexane) reveals three maxima:

3 aexm 273.19.2X103 23211.05X104 To prepare carboranylmethyl[(ortho-methoxy)benzoate], heat 175 ml. of toluene containingcarboranylmethyl alcohol (8.7 g., 0.05 mole) to 65 C. under nitrogenatmosphere. To this hot solution add 9.5 g. (0.055 mole) ofortho-methoxybenzoyl chloride dropwise over a period of 15 minutes. Heatthe mixture to 75 C. for 3 hours. Flush the reaction mixture withnitrogen to remove the residual hydrogen chloride gas. Cool the reactionmixture to room temperature and remove the toluene under vacuum.Neutralize the residue with 5% sodium bicarbonate solution and filter toget the crude carboranylmethyl- (o-methoxy)benzoate, M.P. 83.85 C.Recrystallize the crude product three times from cyclohexane to givecolorless fine needles of product M.P. 86-87" C.

Analysis.-Calcd. for C I-1 13 0 C, 42.7; H, 6.49; B, 35.0. Found: C,41.67; H, 6.54; B, 34.62.

The UV spectrum (cyclohexane) reveals two maxima:

To prepare carboranylmethyl [(para-methoxy)benzoate] add 9.4 g. (0.055mole) of para-methoxybenzoyl chloride dropwise to 8.7 g. (0.05 mole) ofcarboranylmethyl alcohol in ml. toluene under nitrogen. Heat the mixturefor two hours at 100 C. and work-up the product as in the previousembodiments. is obtained, M.P. 98-102" C. Upon recrystallization twicefrom cyclohexane a colorless fine needle-like product is obtained, M.P.102-104 C.

Analysis.Calcd. for C H B O Found: C, 42.26; H, 6.59.

The UV spectrum (cyclohexane) reveals one maxima:

To obtain 1,2-bis [(o-hydroxy)benzoyloxyrnethyl] carborane reflux amixture of bis(hydroxymethyl)carbo,--

A crude product;

1,2-bis [(o-hydroxy)benzoyloxymethyl] carborane, M.P. 166168 C. Whenrecrystallized from cyclohexane a needle-like material, M.P. 175-176 C.was obtained. Analysis.-Calcd. for C H B O C, 47.9; H, 5.45; B. 24.4Found: C, 48.01; H, 5.74; B, 24.72.

The UV spectrum (cyclohexane) reveals two maxima:

dry, and recrystallize twice from cyclohexane to give a colorlessneedle-like solid product, M.P. 100102 C.

Analysis.Calcd. for C H B O C, 51.0; H, 5.97. Found: C, 51.3; H, 6.51.

The UV spectrum (cyclohexane) reveals two maxima:

To prepare 1,2-bis [(p-methoxy)benzoyloxymethyl] carborane, heat amixture of borane (10 g., 0.05 mole) and para-methoxybenzoyl chloride(18.7 g., 0.11 mole) in 150 ml. of dry toluene at 75 C. for a three hourperiod until the HCl is evolved. Workup the crude product, 1,2-bis[(p-methoxy)benzoyloxymethyl] carborane, M.P. 100102 C. andrecrystallize the compound twice from cyclohexane to yield a colorlesssolid, M.P. l03104 C.

Analysis.Calcd. for C H B O C, 51.0; H, 5.97; B, 22.91. Found: C, 50.68;H, 6.17; B, 22.67.

The UV spectrum (cyclohexane) reveals one maxima:

by refluxing a reaction mixture of cinnamoyl chloride (0.2 mole),hydroxymethylcarborane (0.2 mole) and xylene (150 ml.) for 5 hours.After recrystallization from hexane a crystalline product was obtainedWhose structure was proved by elemental analysis.

To prepare the tri-(carboranylmethyl) ester of trimesic acid(1,3,5-benzenetricarboxylic acid) heat (0.16 mole) quantity ofbis(hydroxymethyl) carborane in 150 ml. of dry toluene to 65 C. under anitrogen atmosphere. Add trimesic acid (0.05 mole) dropwise over aperiod of minutes. Heat the mixture to 80 C. for a three hour period toremove water as an azeotrope. Cool the reaction mixture vacuum, dry, andrecrystallize twice from cyclohexane to give the purified tn'esterproduct. Elemental analysis was used to establish the purity of theproduct.

To prepare the dicarboranylmethyl ester of terephthalic acid, heat amixture of bis(hydroxymethyl)carborane (0.11 mole) and terephthalylchloride (0.05 mole) in desired product by analysis.

To prepare the diester from bis-(Z-hydroxymethyl-lcarboranylmethyl)ether of benzoic acid, heat 0.2 mole of the above ether with 0.4 mole ofbenzoyl chloride in 150 ml. of dry toluene at C. for 4 hours untilevolution of HCl was substantially complete. Work-up andrecrystallization yielded a solid ester product which was confirmed byelemental analysis.

This invention is advantageous in both its composition and processaspects.

For example, in its composition aspect this invention olfers a series ofnovel compounds useful as organic intermediates, polymer intermediatesand as additives for stabilizing materials toward ultraviolet attack.

In its process aspects, the invention offers several advantagesincluding good yields, flexible reaction conditions, a wide choice ofreactants and availability of these reactants such as the preferredaromatic rnonoand dibasic acids, and acid chlorides are known compoundsin some instances available in commercial quantities. The carboranereactants such as the mono-hydroxyalkyl carboranes and thebis(hydroxyalkyl)carboranes can be prepared by a number of methods.

For example, the 1,2-bis(hydroxyalkyl) carborane reactants of thisinvention may be prepared by the interthen hydrolysis with aqueoushydrogen chloride to 1,2- bis(hydroxymethyl) carborane. This diol canalso be prepared by reducing 1,2-bis (acetoxymethyl) carborane withlithium aluminum hydride.

The l-hydroxyalkylcarborane or mono-hydroxyalkylcarborane reactants areprepared similarly by contacting the monoacetate esters of theappropriate acetylenic monohydric alcohol with 6,9-bis(acetonitrile)decarborane to yield the l-(acetoxyalkyl) carborane and hydrolyzing inaqueous acid or base to form the l-hydroxyalkylcarborane. For example,the lowest member of the series, I-hydroxymethyl carborane, can beprepared by reacting propargyl acetate with bis(acetonitrile) decaboraneand hydrolyzing the intermediate to the l-hydroxymethylcarborane. Adescription of the preparation of those compounds in aryl or halogensare substituted The bis(hydroxyalkyl)neocarborane reactants may beprepared among other methods through the dilithium derivatives ofneocarborane i.e. neo-Li-C-B H -C-Li. For example, bis(hydroxyethyl)neocarborane may be prepared by reacting neo-Li-C-B H -OLi with 2 molesof ethylene oxide. The higher and lower homologues can be prepared byusing the appropriate Grignard reactant of neocarborane molecule andethylene oxide.

Similarly the mono-hydroxyalkylneocarborane can be prepared by reactingthe monolithium neocarborane (neo- Li-C-B H -CH) or appropriate Grignardreagent with the same class of reactants, i.e. ethylene oxide.

As the numerous embodiments indicate modifications of reactionconditions, reactants and the like can be made without departing fromthe inventive concept.

While all of the ester compositions of this invention are of interest asintermediates, the preferred esters are the benzoic and salicylic estersof the hydroxyalkylcarboranes in which the'alkyl group has from l8carbon atoms and The metes and bounds of this invention are best dewherethe aromatic nucleus can contain one or more adfined by the claims whichfollow.

ditional inert substituents such as lower alkyl, lower allr- We claim?oxy, halogen and hydroxy. These esters are readily pre- \A salicylicacid ester of monohydroxyalkylcarbopared from commercially availablearomatic acid or the 5 Times and di-hydroxyalkylcal'bCranes, Said alkylgroups acid chlorides and are good ultraviolet absorbers. These havingfrom 9 atomssalicycli'c and benzoic esters are advantageous compared ito the aliphatic, esters of the carborane alcohols and diols,Referencesclted in'that the aromatic esters are potent U.V. absorbersand Y i STATES N v the aliphatic'esters are not. Further, the aromaticesters 19 3 ,2()3 ,9=79 Q3/1959 Ager et a1 260- 491- of this inventionhave much greater thermal stability than 3,135,786 6/1964 Ager et'al.-'26 0-6( )6.5 X do the corresponding aliphatic esters and for thisreason a i i v V i 1 can be used as heat transfer materials where thealiphatic LORRAINE IWEINBERGER Primal? Exam-in?- materials would beunsatisfactory. D. E. STENZEL; Assistant Exa r niner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,409,663 November 5, 1968 Saiyid M. Naqvi et a1.

It is certified that error appears in the above identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 8, after line 6, insert 2. Carboranylmethyl salicylate.

In the heading to the printed specification, line 9, "1 Claim" shouldread 2 Claims Signed and sealed this 23rd day of February 1971.

(SEAL) Am:

Edward M. Fletcher, Jr.

Attesting Officer Commissioner of Patents WILLIAM E. SCHUYLER, JR.

1. A SALICYCLIC ACID ESTER OF MONOHYDROXYALKYLCARBORANES ANDDI-HYDROXYALKYLCARBORANES, SAID ALKYL GROUPS HAVING FROM 1-8 CARBONATOMS.